Prelims 2011 · archive
EasyConsider the following statements:
- 1.Biodiversity is normally greater in the lower latitudes as compared to the higher latitudes.
- 2.Along the mountain gradients, biodiversity is normally greater in the lower altitudes as compared to the higher altitudes.
Which of the statements given above is/are correct?
Answer & explanation
Answer: (c) Both 1 and 2
Both statements are correct, so the answer is (c). Species richness is highest in the tropics and falls towards the poles. On mountains, temperature drops steadily with height, so the warmer lower slopes usually hold more species than the cold upper slopes. Both statements describe the normal pattern.
- ✓ 1. Biodiversity shows a latitudinal gradient: richness is highest near the equator and falls towards the poles. Birds show this clearly. Colombia, near the equator, has nearly 1,400 bird species, New York (41° N) has 105 and Greenland (71° N) only 56.
- ✓ 2. Mean temperature falls as elevation rises, so a mountain is divided into thermal belts, each with its own flora and fauna. The warmer, less harsh lower belts generally support more species than the cold, harsh upper belts. This is the normal pattern, though local exceptions exist.
- ✗ (a) This option accepts only the latitude statement. It wrongly rejects the altitude statement, which also describes the normal pattern.
- ✗ (d) The decline in species richness from the equator towards the poles is well established, so rejecting both statements is wrong.
Remember · Species richness normally declines from the equator to the poles and from lowlands to high altitudes. Colder, harsher conditions support fewer species.
📘 Read it in NCERT: Class 12 Biology, Ch 13 (practise this chapter)
Sources
- NCERT Class 12 · Biology, Chapter 13 “Colombia located near the equator has nearly 1,400 species of birds while New York at 41° N has 105 species and Greenland at 71° N only 56 species.”
- FAO – Mountain Biodiversity and global change ↗ “As elevation increases, mean temperature decreases. Mountains are thus stratified into thermal belts, each with a characteristic flora and fauna”
Question: UPSC Civil Services (Preliminary) 2011, General Studies paper. Explanation: Minimalist IAS, checked 25 Oct 2026 (how we verify). ·